Abstract  In December 1981, the National Institute for Occupational Safety and Health (NIOSH) received a request to evaluate occupational exposure to chlorinated solvents at Pratt & Whitney Aircraft (P&WA). West Palm Beach, Florida. The request was prompted by reported findings of elevated blood chloroform levels and an increased prevalence of cancer in the workforce. Industrial hygiene and medical surveys were conducted 1n December 1981 and March 1982. The industrial hygiene evaluation included; 1) full shift and short term air sampling using standard charcoal sorbent tubes and a photoionization detector to evaluate current solvent exposures of 30 degreasor operators, 2) review of past industrial hygiene ·sampling data and, 3) water sampling to evaluate trihalomethane contamination levels. The medical evaluation included; 1) review of the "blood-chloroform" test, 2) pre- and post-shift urine sampling to monitor total trichloro compounds (TCC), 3) questionnaire survey and, 4) evaluation of cancer mortality using a proportional mortality ratio (PMR), a proportional cancer mortality ratio (PCMR) to correct for some inherent biases in the PMR and a case control study to determine if persons who died of cancer were more likely to have worked in areas of higher solvent exposures. Eight-hour, TWA concentrations ranged from 0.3 to 22.9 ppm for Trichloroethylene (TCE), 0.8 to 7.2 ppm for Perchloroethylene (PERC), and 0.5 to 2.0 ppm for Methylch1orofonn (MC). All were well below the current OSHA standards (TCE-100 ppm, PERC-100 ppm, MC-350 ppm) and below the 25 ppm considered by NIOSH to be achievable using engineering controls. NIOSH recommends that TCE and PERC be considered human carcinogens and therefore exposures minimized and that MC be handled with caution due to its chemical similarity to TCE and PERC. The urine test results, which measured total trichloro compounds (TTC) in post shift samples and ranged from 0.5 to 83.0 ug/gr, showed good correlation {R=0.92) with the 8-hour TWA exposure data. Peak exposures to degreasing solvents were estimated to be in the 200-300 ppm range. Occasional symptoms such as lightheadedness, headache and eye irritation reported by 20-30% of those interviewed. suggests that peak levels may occasionally exceed these values. Past environmental data indicates that 8-hour TWA exposures to degreasing solvents were generally below 25 ppm back as far as TWA data was available (1973). Analysis of water samples indicated that the new aeration units are maintaining tri-halo-methane {THM) concentrations below 0.2 ppm which is on the low end of the range (0.2-1.0 ppm) normally found in the surrounding localities. It's possible that exposures to background concentrations of chlorinated solvents, which average 2-5 ppm in the plant, are responsible for a significant portion of the reported blood-chloroform concentrations. A PMR of 156 for all cancers suggests that a 56S increased proportion of mortality due to cancer was present in this group. However. for the seven individual cancer death categories that appeared statistically significant in the PMR analyses. none remained elevated in the PCMR. This indicates that the elevated PMR was artifactual. Furthermore. there was no indication. from the case control study, that those persons who died of cancer were any more likely to have worked in an area of higher degreasing solvent concentrations than their matched controls who died of some other cause.